Metal sheet used in industry to create different-shaped pieces by means of, for example, pressing, stamping or forming is provided in the form of rolls or coils of metal. The coils must be uncoiled in order for the metal sheet to be handled and when this is done the sheet features undulations and distortions that are detrimental to its subsequent treatment or handling. In order to solve this drawback the sheet to be unrolled must be handled by a straightening machine where most of the stresses are eliminated. These straightening machines generally comprise a plurality of rollers between which the sheet passes.
This process is suitable for cases in which the sheets comprise a limited thickness. If the thickness exceeds a certain value, the rollers required to eliminate the stresses are very large, making the elimination of stresses in this way difficult. In these cases a drawing machine such as the one disclosed in document EP1923150A1 may be used, by means of which the sheet is drawn to eliminate the stresses. This method can also be used for sheets of limited thickness. A drawing machine generally comprises a fixed support and a moving support that moves in relation to the fixed support in a drawing process. Both supports comprise a window through which the metal sheet to be drawn passes, and a holder for holding the metal sheet during the process with the aim of ensuring it is drawn. During the process of drawing metal sheet, due to the forces generated by the holder and the tension of the metal sheet, the supports suffer deformations that weaken them over time.